Method of making tandem solar cell module

Abstract

A tandem solar module and a method for the manufacture thereof. The tandem solar module has a first, large-area, lower solar sub-module of polycrystalline silicon (c-Si), has an electrically insulating, transparent intermediate layer functioning as an optical coupler, and also has a second, transparent, upper sub-module of amorphous, hydrogenated silicon (a-Si:H). Both sub-modules are provided with mutually independent electrical contacts and each is functional in and of itself. An active material in the first sub-module that is preferably structured strip-shaped can be composed of silicon strips produced in a band drawing method. The second sub-module is executed in thin-film technology in a known way and has a p-i-n structure. Its substrate serves as a covering for the overall module. The tandem solar module exhibits high efficiency and is cost-effective to be manufactured. It can be manufactured with a large-area and exhibits high long-term stability.

What is claimed is: 
     
       1. A method for manufacturing a tandem solar cell module comprising the steps of: (a) applying an electrically conductive layer on a substrate of electrically insulating material that has bars proceeding parallel to one another at defined spacings from one another, said layer being applied between said bars;   (b) inserting between the bars strips of p-doped, polycrystalline silicon fitting over the conductive layer, and the strips being connected to the conductive layer in an electrically conductive fashion thereby defining a plurality of strip-shaped individual solar cells;   (c) forming a pn-junction in each of the silicon strips;   (d) providing holes that extend to the surface of the conductive layer in the silicon strips, the holes being provided at the end of said strips;   (e) applying a strip pattern forming front-side contacts to the strip-shaped, individual solar cells with a silk screening process, said strip pattern being composed of an electrically conductive paste;   (f) providing an electrically conductive connection between the front-side contact and the conductive layer of a neighboring individual cell, the conductive layer forming a back-side contact of individual solar cells and being exposed in the holes;   (g) providing the strip-shaped solar cells, series-connected to form a first sub-module, with an anti-reflection layer;   (h) joining via an optical coupler the first sub-module to a second previously manufactured sub-module of amorphous, hydrogenated silicon solar cells that is of the same size, so that a substrate of the second sub-module forms a covering for the tandem solar cell; and   (i) integrating the overall module into a frame, whereby independently provided photocurrent generated by the individual sub-modules is provided via a total of at least four electrical contacts.   
     
     
       2. The method according to claim 1, wherein the height and spacing of the bars relative to one another is fashioned such that depressions between the bars correspond exactly to the size of the silicon strips to be accepted therein. 
     
     
       3. The method according to claim 1, wherein the pn-junction in the cells of the first sub-module is produced by phosphorus ion implantation. 
     
     
       4. The method according to claim 1, wherein the production of the pn-junction in the silicon strips of the first sub-module according to method step c) is undertaken before the strips are placed between the bars. 
     
     
       5. The method according to claim 1, wherein the pn-junction in the cells of the first sub-module is produced by drive-in of phosphorus into the silicon.